Folder Virtualization is a feature of Vista that allows virtualizing installation folders into a virtual store so that users who normally wouldn't be able to modify data in the Program Files folder get a private 'shadow' store so they can write to data. Interesting feature and certainly not very obvious...

Oh man, I’m going to REALLY hate Vista from an application installation and configuration perspective for custom applications. To make a long story short, pretty much none of my Windows applications run or in some cases don't install under the default Vista security configuration.